Laser on a silicon chip Holy Grail of incredibly fast communications

The Holy Grail of incredibly fast communications – a laser on a silicon chip – has been achieved in an incredible breakthrough by a team of British scientists. The researchers say their first practical silicon laser has the potential to completely transform energy, healthcare and communications systems.

The research, led by scientists from Cardiff University, who worked alongside academics from University College London (UCL) and the University of Sheffield, claim they have demonstrated the first practical laser that has been grown directly on a silicon substrate (underlying substance).

Breakthrough could transform several sectors

They say their breakthrough could lead to mega-fast communication between computer chips and electronic systems, which would completely transform a vast range of sectors.

(A) Schematic of the layer structure of an InAs/GaAs QD laser on a silicon substrate. (B) A cross-sectional SEM image of the fabricated laser with as-cleaved facets, showing very good facet quality. (C) SEM overview of the complete III–V laser on silicon. (Image: nature.com)

Details on the research, which was funded by the Engineering and Physical Sciences Research Council (EPSRC), have been published in the prestigious journal Nature Photonics (citation below).

Silicon is the most commonly-used material in the manufacture of electronic devices. It is used to make semiconductors, which are embedded into virtually every device and piece of technology that people use in their everyday lives, from GPS and satellite communications to smartphones, computers and medical devices.

Current technology struggling with growth

Electronic devices have been getting faster, more efficient and significantly more complex, and have consequently placed an additional demand on the underlying technology, which many say is bursting at the seams.

Scientists say keeping up with this ever-growing demand using conventional electrical interconnects between computer chips and systems is a race we will eventually lose. That is why they have turned to light as a potential super-fast connector.

Silicon photonics is a futuristic technology in which data is transferred among computer chips by optical rays (light). Optical rays can carry considerably more data in less time than electrical conductors.

The main obstacle has been combining a semiconductor laser – the ideal light source – with silicon. In fact, scientists wondered whether it might be impossible, that is, until this latest breakthrough.

The British team have now overcome these obstacles and managed to successfully integrate a laser directly grown onto a silicon substrate for the first time.

Leader of the growth activity, Huiyun Liu, Professor of Semiconductor Photonics at UCL’s Department of Electronic & Electrical Engineering, explained that the 1300 nm wavelength laser has been shown to operate at temperatures below 120°C (248°F) for up to 100,000 hours.

Silicon photonics is the future

Professor Peter Smowton, Deputy Head of Cardiff University’s School of Physics and Astronomy and Director of Research, said:

“Realising electrically-pumped lasers based on Si substrates is a fundamental step towards silicon photonics. The precise outcomes of such a step are impossible to predict in their entirety, but it will clearly transform computing and the digital economy, revolutionise healthcare through patient monitoring, and provide a step-change in energy efficiency.”

“Our breakthrough is perfectly timed as it forms the basis of one of the major strands of activity in Cardiff University’s Institute for Compound Semiconductors and the University’s joint venture with compound semiconductor specialists IQE.”

Dr. Huiyun Liu (pictured above) and his research team have created a laser that can grow on one single silicon chip. What they have done is provided a method to generate the light actually on the chip itself. That is the Holy Grail of silicon photonics. (Image: From YouTube video below)

Head of the Photonics Group at University College London, Professor Alwyn Seeds said:

“The techniques that we have developed permit us to realise the Holy Grail of silicon photonics – an efficient and reliable electrically driven semiconductor laser directly integrated on a silicon substrate.”

“Our future work will be aimed at integrating these lasers with waveguides and drive electronics leading to a comprehensive technology for the integration of photonics with silicon electronics.”

As silicon chips get progressively faster, the copper connections used to transmit electrical signals between them are struggling to keep up. The obvious next step must be optical signals. However, integrating them with silicon systems is difficult.